Slovenian hop plantations are threatened by three different viroids: hop latent viroid (HLVd), hop stunt viroid (HSVd) and citrus bark cracking viroid (CBCVd). The purpose of this master's thesis was to examine a large number of hop cultivars for susceptibility to infection with viroids (HLVd, HSVd and CBCVd), which threaten Slovenian hop farms. During the experiment, we grew different hop cultivars in in vitro conditions: we prepared the culture medium, subcultivated the plants onto fresh culture media, and monitored the growth of the plants. We prepared viroid transcripts, validated the performance and relevance of the transcripts with an Agilent Bioanalyser 2100 device, and then infected hop plants in tissue cultures with viroid transcripts and documented the growth and development of infected and uninfected plants. After eight weeks, confirmation of the success of hop infection followed with the RT-PCR method and gel electrophoresis were conducted. Our data showed that using our newly established method of viroid inoculation we have successfully infected all hop cultivars using viroid transcripts. Interestingly, the rate of infection was the highest for HSVd transcripts (100 % for all 13 cultivars), followed by CBCVd (100 % for 9 cultivars and 75 % for 4 cultivars) and the lowest for HLVd (75 % for 3 cultivars, 50 % for 5 cultivars and 25 % for 3 cultivars). Up to date, we did not observe any difference in growth and development of infected and uninfected plants and we did not discover any possible resistance or tolerance in tested varieties. Plants of cultivars 'Wye Target' and 'Bobek' were already infected with HLVd before the start of our work and in this case the plants were not virus and viroid free.
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